Multimodal large language models (MLLMs) are effective at capturing the semantics of short video content; however, they often fail to attend to the policy-specific details required for reliable content moderation.To address this limitation, we introduce IPS, a novel framework that integrates In-prompt Process Supervision into MLLMs by introducing sequential reasoning over ancillary questions during fine-tuning. IPS consistently outperforms baseline MLLMs on public and proprietary benchmarks.Moreover, replacing human-annotated ancillary labels with MLLM-generated ones results in only marginal performance degradation, demonstrating robustness to noisy supervision and strong scalability with model-generated annotations.These findings establish IPS as a scalable and effective solution for complex multimodal classification in large-scale industrial settings.

Short video platforms are evolving rapidly, making the identification of inappropriate content increasingly critical.Existing approaches typically train separate and small classification models for each type of issue, which requires extensive human-labeled data and lacks cross-issue generalization.We propose a reasoning-enhanced multimodal large language model (MLLM) pretraining paradigm for unified inappropriate content detection. To address the distribution gap between short video content and the original pretraining data of MLLMs, as well as the complex issue definitions, we introduce three targeted pretraining tasks:(1) Caption, to enhance the MLLM’s perception of video details;(2) Visual Question Answering (VQA), to deepen the MLLM’s understanding of issue definitions and annotation guidelines;(3) Chain-of-Thought (CoT), to enhance the MLLM’s reasoning capability.Experimental results show that our pretraining approach significantly improves the MLLM’s performance in both zero-shot and supervised fine-tuning (SFT) settings.In addition, our pretrained model demonstrates strong generalization capabilities to emergent, previously unseen issues.